Japanese Unexamined Patent Publication No. JP2006-290710A discloses a method of manufacturing optical fiber preform and optical fiber. The method disclosed in JP2006-290710A preliminarily acquires change of a refractive index profile in a manufacturing process of optical fiber, and then adjusts at least one of manufacturing conditions of optical fiber preform and optical fiber on the basis of the change.
Japanese Unexamined Patent Publication No. JP2014-534944A discloses a method of manufacturing optical fiber. In the method disclosed in JP2014-534944A, first, preform is provided inside a furnace, and a plurality of optical fibers are drawn from the preform at a plurality of different levels of drawing tension. Then, bandwidth characteristics of the plurality of optical fibers are measured, and a setting value of drawing tension of an optical fiber is selected so that the optical fiber at the setting value has bandwidth characteristics close to desired bandwidth characteristics.